As limitations in exhaust gas of a vehicle are reinforced, a post-processing device for cleaning exhaust gas has been developed.
Exhaust gas exhausted from a gasoline vehicle or a diesel vehicle using gasoline or diesel as a fuel includes carbon monoxide, hydrocarbons, nitrogen oxides, sulfur oxides, and particulate matter.
Particularly, a particulate matter (PM) in the diesel vehicle accelerates generation of a floating dust as a main cause of air pollution. Accordingly, limitation of the PM is very strict.
In order to reduce the PM in the diesel vehicle, a diesel particulate filter (DPF) is part of an exhaust system, and a particulate matter sensor is used to detect an amount of soot captured in the DPF.
The particulate matter sensor detects variation in resistance or capacitance generated when a particulate material included in exhaust gas is accumulated in the sensor, and is installed at a rear end of the DPF.
The particulate material sensor may be classified into an accumulation sensor and a real time sensor.
The accumulation particulate matter sensor is used for the majority of vehicle components, and detects variation of a current flow when the particulate matter is accumulated at two digital electrodes to which a voltage is applied.
Since the accumulation particulate matter sensor has a simple sensor configuration, reliability is high and a manufacturing cost is low so that the accumulation particulate matter sensor is suitable for the vehicle.
The real time particulate matter sensor may monitor an amount of a particulate matter in real time by detecting an ionization reaction of the particulate matter.
However, the particulate matter sensor according to the related as described above requires an initial accumulation time until a current variation signal is generated, and requires a complicated sensor structure for determining breakage of the diesel particulate filter.
Further, accuracy of the particulate matter sensor decreases and a size of the particulate matter sensor increases so that it is difficult to miniaturize the particulate matter sensor.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention, and therefore, it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.